Expressions - Double name strap with with BG layer that follows the lines of text in height

So you have one caption saying:

ShveringCactus

ACP

And after 7 seconds, a second caption appears alongside saying:

KJAE

New Here

So you want them both to appear on one layer with the background growing to accomodate them, something like:

ShveringCactus                          KJAE

ACP                                            New here

If that's the case, have you considered using a Pre-Comp with Essential Graphics properties?  You know the timings, you could have each text on its own layer and have the background respond to the two top lines with code like:

var message1 = comp("CTRL").layer("page").text.sourceText;

var message2 = comp("CTRL").layer("page2").text.sourceText;

if (message1 == ""){
thisProperty = [0,0]
} else {
thisProperty = [0,-20]

if (message2 !== "" and time > 7){

    thisProperty = [0,-100]

}
}

If you only have one text layer and a shape layer behind the text, use this for the shape layer's size.

var paddingx = 10;
var paddingy = 10;
var x = thisComp.layer("asdfasdfasd asdfasfd").sourceRectAtTime(time).width + paddingx;
var y = thisComp.layer("asdfasdfasd asdfasfd").sourceRectAtTime(time).height + paddingy;
[x,y];

And use this for the text's anchorpoint so the anchorpoint remains in the center.

boxTop = thisLayer.sourceRectAtTime(time).top;
boxHeight = thisLayer.sourceRectAtTime(time).height;
boxLeft = thisLayer.sourceRectAtTime(time).left;
boxWidth = thisLayer.sourceRectAtTime(time).width;
[boxLeft + boxWidth/2, boxTop + boxHeight/2 ];

Let me know if it works! 🙂

I can't make sense of your description or your code snippet. then again it's evening around here and I'm kind of tapped out. Anyway, clearly you must be using otehr code fragments to actually make your BG scale rather than just move, so it would be more useful if you actually posted a screenshot and the full code. Technically functions like sourceRectAtTime() don't discriminate and really base their calculations on the layer content size, regardless how many lines your text has, so I'm not sure what you are having issues with.

Mylenium